Device for annealing metallic articles.



A. KREIDLER.

, DEVICE FOR ANNEALING METALLIC ARTICLES.

APPLICATION FILED DBO. 6, 1911.

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DEVICE FOR ANNEALING- METALLIC ARTICLES.

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Specification of Letters Patent.

Patented Sept; 17,1912.

Application filed December 6, 1911. Serial No. 664,198.

all to/tom it may concern: Be it known that I, An'roN KREIDLER, manufacturer, a Sl1l)]0li of the German Emperor, and resident of Stuttgart, Germany,

with the post-ollice address Hasenbergsteige it, have invented new and useful Improve merits in Devices for Annealing Metallic Alllillfifi, of which the following is aspecilication.

The invention relates to healing metallic articles. It is based on the known method in which metallic articles are conducted through an annealing retort by means of an endless conveyer consisting of a chain or belt, or of an annealii'ig truck running on rollers. In this instance the oonveyer runs through pipes which are connected in an air-tight manner with the retort and in the interiorv of which pipes, as in the retort, an atmosphere ot' non-oxidizing gases, such as nitrogen, hydrogen, carbon dioxid or the vapors of liquids is maintained, in order to prevent the oxygen of the atmosphere from coming in contact with the glowing or hot articles and oxidiz. ng them. In order to afi'ord further protedtion against the admission of atniospherie air, the open ends of the said pipes dip either intowater-as; is done, for Instance, 1 German Patent 138 520or else the gas itself forms a seal shutting out atmospheric air, inasmuch as the pipes are led "away, from both sides of theretort, for example dowmvard for a short distance and r then. upward, or first upward and then downward. in the latter event, a seal shutting or? contact with the exterior, isin;

tended to be formed by the monoxidizing Y gases themselves, if the latter belighter than ir (German Patent. No. 163415). .In all known appliances of this kind the pipes issue/from both sides or the retort and reunite it" oxidized by the oxygen of the air. In order.

s to ,eilect this later, when the articles have been'coolcd (lGlWIl. In this event it is assumed that when the articles, are cool they will no longer be cooling as quickly as possible ,after leaving the retort the pipes are also 1 the cooled, in many cases, by a cooling device.

Vfhen the pipes are excluded from connection with the exterior by means of water, the retort is continually charged with water vapor, which is liberated at the point where hot pipes dip in the water tank. This causes a considerable loss of heat, and moreadevice for an-' For iron and steel articles the other method alone is applicable, namely that in which the exclusion of the atmospheric air is ef-. fected by non-oxidizing gases which are either lighter or heavier than air. In this method, however, a considerable loss of heat is sustained because the entire heatof the hot metallic articles issuing from the retort is lost.

The assumption that in the caseojf gases ofditterntdensity, an absolute exclusion of the one gas can be effected by the other, is erroneous, and is opposed to the law of the diffusion of gases. In reality the behavior of such two gases in relation to each other is such that, when for instance the light gas is" at the top, a gradual mixing takes place downwardly, in such a manner that, for instance, between nitrogen and atmospheric from above downward. To preventoxida: tion of the metallic articles which aremoving in this atmosphere, all that is necessary is to see that the places at whicha, so to speak, injurious content of oxygen is still present are displaced so far downward that the articles will be comparatively cool by the time. they get there. Care mustltherefore be taken that the cooling of the annealed nietallic articles iseileoted' as quickly as possibleafter they issue tram tl retort; but on the other hand, in 'orde facilitate the utilization of the heat, it IS desirable that theheat of the annealed metallic articles should be simply eliminated, as is cllected to a large extent by means of a cooling do vice placed close to the'retort. 4

The novelty of the present invention consists in that an interchange of heat is brought about between the metallic articles entering the retort for the purpose of being annealed, and the annealed articles issuing from the retort. In order to achieve this result the conveyors for the articles fed into the retort and those issuing from the retort, are situated. as close as possible to eachother,

'so that both devices (annealing truck tracks) air, the oxygen content gradually increases are housed in the one pipe or else in two pipes lying close together. The heat of the articles issuing from the retort is then taken up by the articles that are being fed into the retort, and conversely the cool temperature articles on their way to the retort and those issuing from the retort, will attain an equal, comparatively low temperature in a comparatively short time. This temperature will soon be so low that if any atmospheric air finds its way in, the oxygen of same can no longer exert any oxidizing action on the me-.

tallic articles. By this means, moreover, the so-called sealing of the delivery pipein relation to the air-which is always emphasized in-the known methods-becomes entirely suierfiuous. The pipes which house the ,two aulage tracks in common ma be quite open on the side farthest away rom the retort if their length has been properly selected. This absolute freedom of the mouth of the delivery pipe and the adjoining perfectly open curve exposed to the air and on which the trucks are unloaded of the annealed articles and reladen with the articles to be annealed, enables the whole plant to be served in a much ,better and more intensive manner.

It is advisable to slope the entire system in a straight llne when the atmosphere in the' retort and delivery pipe consists of non-,

oxidizing gases which are lighter than air, in order that the highest point may be the hottest,'and the lowest point the coolest. A special upward or downward bend in the deliver]? ipe is regarded as quite superfluous. e ore beginning work, the interior of the retort and delivery pipe is filled with an atmosphere of non-oxidizing gas, such as nitrogen, that is lighter than air, and such gas is also supplie while the apparatus is working. By this means the heavy air is driven back and the critica point at which still active oxygen is found is displaced so far in the downward direction that the metallic articles are already cooled down to.

such an extent by the time they reach that point that oxidation can no longer take place. This operation is assisted by the compartively large masses of metal that are present together in the common discharge pipe at equaltemperature. vEven when any excess of oxygen be resent at the critical point,'-the oxidation is distributed over the total quantity of metal. 7

The device forming the subject of the in- .vention is illustrated in the drawing, Figure 1 being an elevation partly in section and Fig. 2 a plan view partly in section.

The furnace a surrounds the annealing retort 7) 111 the rearward portion of which is situated the curve (7 of the conveying device. The delivery pipe 6 is secured in an air-tight manner to the other end of the rctort; and in the interior of the said pipe the conveylng devices f (preferably trucks run nmg on a track) more in opposite dlrections.

g is the second curve-outside the delivery pipe-on which the conveyor trucks f make their return trip. Both the retort b and the delivery pipe 6, with the conveyer trucks f running inside, are arranged to slope downward in a straight line.

At 2' is a closable pipe connection through which the light, non-oxidizing gases can be introduced.

Now what I claim and desire to secure by Letters Patent is the following:

1. In devices for annealing articles, the combination of a retort, means extending into said retort and arranged to convey the articles into and out of said retort at the same side thereof, and means connected with and extending from said retort ovcr'and covering said conveying means.

2. In devices for annealing metallic articles, the combination of a retort, a conveying device extending into said retort and describing a returning curve therein whereby the articles are moved into and out of said retort at the same side thereof, and means connected with and extending from said retort over and covering said conveying device.

3. In devices for annealing metallic arti{ and extending-from said retort over and 2 covering said conveying device.

4. In devices for annealing metallic articles, the combination of a retort, a convey ing device ext-ending into said retort and describing a returning curve thereinwhereby the articles are moved into. and .out of said retort at the same side thereof, and a common delivery. pipe connected with and extending from said retort and surrounding the feed portion and the return portion of said feeding device.

5. In devices for annealing metallic articles, the combination of a retort, a conveying device extending into said retort, and describing a returning curve therein whereby the articles are moved into and out of said retort at the same side thereof, and a common delivery pipe connected with said retort in an air-tight manner and extending from said retort so as to surround the feed portion andthe retiirn portion of the feedlng device, said delivery pipe being open at the end opposite to that which is connected with the retort.

5 6. In devices for annealing metallic articles, the combination of a retort anda conveyin device extending in the said retort and escribing a returning curve therein whereby articles are moved into and out of 10 said retort at the same side thereof, said conveying device being arranged at an angle v to the horizontal.

7. In devices for annealing meaic articles, the combination of a retort a con- 15 veyin device extending into said retort and descri ing a returning curve therein whereby the articles are moved into and out of said'retort at the same side thereof, said conveying device having its feed portion mas er a other and extending'at an angle to the horjzontal. I

8. In devices for annealing metallic articles, the combination of a retort, a delivery 25 pipe connected with said retort at one end lpe. c In testimony, that I claim the foregoing as my invention, I have signed my name in resence of two witnesses, this 22nd day of ovember1911.

ANTON KREIULER.

Witnesses I PAULINE Kmrmm,

PAULINE MiiLLnn. 

